Abstract: In the particular embodiment of an ink deaerator described in the specification, an elongated ink path leading to an ink jet head is formed between two permeable membranes. The membranes are backed by air plenums which contain support members to hold the membranes in position. Reduced pressure is applied to the plenums to extract dissolved air from the ink in the ink path. Increased pressure can also be applied to the plenums to eject ink from the ink jet head for purging. Within the ink jet head ink is circulated convectively from the orifice to the deaerating path even when the jet is not jetting ink.

Abstract: In the particular embodiment of a device for removing dissolved gas from ink described in the specification, an elongated ink path leading to an ink jet head is formed between two permeable fluorine-containing membranes. The membranes are backed by air plenums which contain support members to hold the membranes in position. Reduced pressure is applied to the plenums to extract dissolved gas from the ink in the ink path without accumulating scum on the membrane surfaces. Increased pressure can also be applied to the plenums to eject ink from the ink jet head for purging. Within the ink jet head, ink is circulated convectively from the orifice to the deaerating path even when the jet is not jetting ink.

Abstract: In the representative ink supply system described in the specification, continuous circulation of ink in an ink jet head is accomplished by providing two reservoirs connected to each ink jet orifice through corresponding passages so that ink flows continuously from a high-level reservoir past the orifice to a low-level reservoir. The difference between the levels of ink in the reservoirs is maintained relatively constant by inertial pumping during reciprocal motion of the ink jet head or by pressure transfer of ink from one reservoir to the other reservoir. Cross-flow purging of air or debris from the ink jet head is effected by covering the ink jet orifices and applying air pressure to one reservoir to cause ink and any trapped air or debris to flow from the head to the other reservoir. A pump responsive to reciprocal motion of the ink jet head generates a positive air pressure which is applied during purging and a negative air pressure which is applied to a deaerator for removing dissolved air from the ink.

Abstract: In the embodiment of the hot melt ink supply unit described in the specification, a block of solid hot melt ink has a peripheral surface formed with a key configuration and a handle is removably connected to the block by a threaded projection. After insertion of the block into a correspondingly keyed opening in a heated reservoir, the handle is turned to separate the handle portion from the block of solid ink. A container provided with a removable seal encloses the block of solid ink and handle to protect the ink from contamination.

Abstract: In the representative hot melt ink supply system described in the specification, a first hot melt ink supply reservoir maintains ink in molten condition during operation of the system and a second reservoir mounted with an ink jet head on a movable carriage communicates with the first reservoir through a flexible supply line. The ink in the supply line is normally kept in solid condition and, when a reduced level of ink is detected in the second reservoir, the supply line is heated to melt the ink in the line and a pump is actuated to transfer ink from the first reservoir to the second reservoir. To permit use of pigmented inks, each of the reservoirs is heated to provide a thermal gradient therein so as to maintain convective circulation of the ink. An ink circulation path is provided to cause convective circulation of pigmented ink in the ink jet head.

Abstract: In the particular embodiment of an ink deaerator described in the specification, an elongated ink path leading to an ink jet head is formed between two permeable membranes. The membranes are backed by air plenums which contain support members to hold the membranes in position. Reduced pressure is applied to the plenums to extract dissolved air from the ink in the ink path. Increased pressure can also be applied to the plenums to eject ink from the ink jet head for purging. Within the ink jet head ink is circulated convectively from the orifice to the deaerating path even when the jet is not jetting ink.